The auditory vesicles develop at the level of the myencephalon.Įmbryology of chicken 72 hours after fertilization: detail of the head in a stained wholemount preparationġ = Auditive (otic) vesicle, 2 = Myelencephalon, 3 = Metencephalon, 4 = Amnion, 5 = Mesencephalon, 6 = Optic bulb, 7 = Lens, 8 = Diencephalon, 9 = Epiphyse, 10 = Telencephalon, 11 = Olfactory grooveĪ. The depression at the ventral side of the diencephalon develops in to the hypophysis ( hypo= under not visible in this fig.). The dorsal projection of the dieencephalon is also visible and will differentiate in to the epiphysis (epi= at the upper side). The eye vesicles differentiate as two lateral projections of the diencephalon and come in contact with the external layer (ectoderm) to form the optic cup (neurectoderm) and the lens (ectoderm). The further development of the five brain vesicles (telencephalon, diencephalon, metencephalon, mesencephalon and myencephalon) in to the different head structures is clearly visible. The development of the brain is shown at higher magnification. The fore and hind limbs at the level of the 16 th to the 20 th respectively the 27 th to the 32 th somite pairs are visible as small buds at an incubation time of about 3 days.Įmbryology of chicken 72 hours after fertilization: stained whole-mount preparation.ġ = Auditive (otic) vesicle, 2 = Myelencephalon, 3 = Metencephalon, 4 = Amnion, 5 = Mesencephalon, 6 = Optic vesicle + lens, 7 = Diencephalon, 8 = Epiphyse, 9 = Telencephalon, 10 = Branchial arches, 11 = Heart, 12 = Forelimb (wing) bud, 13 = Vitelline arteria/vein, 14 = Hindlimb (leg) bud, 15 = Tail Due to the cranial flexure, the pharyngeal region (= region of the trachea) is now located at the ventral side of the head. The fourth pharyngeal groove develops and the pharyngeal arches are thicker.

The two flexures in the head region are almost completed. Whole-mount preparation 72 hours after fertilizationħ2 Hours after fertilization, the rotation of the embryo to the left is arrived such behind the region of the heart and only the caudal part of the embryo must twist 90 degrees.

96 Hour Chick Embryo Serial Section